I've learned a lot in this forum, many thanks to everyone here.

I've successfully made hi-res still mpegs with audio for SVCDs using i-Author. However so far I've only had luck making PAL stills. I can't find a switch or setting anywhere to make NTSC stills. When I tried inputting an NTSC-sized (704x480) BMP into i-Author's encoder, it outputted a PAL mpeg with a black bar at the bottom (presumably for the extra 96 pixels of PAL vertical resolution). Actually perhaps that's not strictly true. It made an MPEG that looked fine on the computer, but had the black bar when displayed on my TV by my standalone DVD player.

A couple of questions then:
1. how can I make hi-res NTSC still using i-Author?
2. if I have an NTSC movie with a PAL still MPEG menu, is that a problem? Is it still standards-compliant, or is it then an XSVCD?

(I should also mention that I'm using the PS switch and renaming the .PS files to .MPG files, to be used by TSCV)